Monster-in-law: Diana Costarakis, 70, was arrested this week after attempting to pay an undercover cop $5,000 to kill her daughter-in-law

A 70-year-old Florida woman was arrested after soliciting an undercover detective to kill her daughter-in-law, authorities said.

Diana Reaves Costarakis, of Middleburg, was being held without bond in the Duval County Jail on Saturday on charges of criminal solicitation and criminal conspiracy, both capital felony crimes, jail records show.

She was scheduled to appear in court on October 31. The records did not list any attorney for her.

According to a police report from the Jacksonville Sheriff's Office, Costarakis offered an undercover detective $5,000 on Wednesday when they first met at a Home Depot.

She gave him $500 as the first payment as well as a photo of the daughter-in-law, her address, and a description of her car, the report said.

Costarakis gave the detective another $1,000 on Thursday and told him her daughter-in-law wore diamonds and other expensive jewelry that could be stolen and sold, with the proceeds being used toward the final payment.

The diamonds could not be traced, she told the detective, according to the report.

When asked if Costarakis wanted her daughter-in-law dead, she said, 'If you don't, I will,' according to the police report.

She was later taken into custody.

Costarakis told police that her daughter-in-law was a drunk and a bad mother to her 6-year-old granddaughter.

Claims: Diana Costarakis told the undercover officer that her daughter-in-law, above, was a drunk and a bad mother to her 6-year-old granddaughter

Angela Costarakis told Action News Jax that the murder plot came out of the blue, since she saw her mother in law three weeks ago and everything seemed fine.

'She gave me a big old hug and said "I'm grad we're great friends,"' Angela said. 'I guess if I was out of the way she could have her son and granddaughter to herself.'

But Angela told WJXT TV on Friday that she still has compassion for her mother-in-law.